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Revision 38e87880666091fe9c572a7a2ed2e771d97ca5aa authored by Chris Mason on 10 June 2011, 20:36:57 UTC, committed by Chris Mason on 10 June 2011, 20:36:57 UTC 
Btrfs: make sure to recheck for bitmaps in clusters
 
Josef recently changed the free extent cache to look in
the block group cluster for any bitmaps before trying to
add a new bitmap for the same offset.  This avoids BUG_ON()s due
covering duplicate ranges.

But it didn't go quite far enough.  A given free range might span
between one or more bitmaps or free space entries.  The code has
looping to cover this, but it doesn't check for clustered bitmaps
every time.

This shuffles our gotos to check for a bitmap in the cluster
for every new bitmap entry we try to add.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
1 parent 3473f3c
Raw File
extable.c 
/*
 * Derived from arch/ppc/mm/extable.c and arch/i386/mm/extable.c.
 *
 * Copyright (C) 2004 Paul Mackerras, IBM Corp.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/sort.h>
#include <asm/uaccess.h>

#ifndef ARCH_HAS_SORT_EXTABLE
/*
 * The exception table needs to be sorted so that the binary
 * search that we use to find entries in it works properly.
 * This is used both for the kernel exception table and for
 * the exception tables of modules that get loaded.
 */
static int cmp_ex(const void *a, const void *b)
{
	const struct exception_table_entry *x = a, *y = b;

	/* avoid overflow */
	if (x->insn > y->insn)
		return 1;
	if (x->insn < y->insn)
		return -1;
	return 0;
}

void sort_extable(struct exception_table_entry *start,
		  struct exception_table_entry *finish)
{
	sort(start, finish - start, sizeof(struct exception_table_entry),
	     cmp_ex, NULL);
}

#ifdef CONFIG_MODULES
/*
 * If the exception table is sorted, any referring to the module init
 * will be at the beginning or the end.
 */
void trim_init_extable(struct module *m)
{
	/*trim the beginning*/
	while (m->num_exentries && within_module_init(m->extable[0].insn, m)) {
		m->extable++;
		m->num_exentries--;
	}
	/*trim the end*/
	while (m->num_exentries &&
		within_module_init(m->extable[m->num_exentries-1].insn, m))
		m->num_exentries--;
}
#endif /* CONFIG_MODULES */
#endif /* !ARCH_HAS_SORT_EXTABLE */

#ifndef ARCH_HAS_SEARCH_EXTABLE
/*
 * Search one exception table for an entry corresponding to the
 * given instruction address, and return the address of the entry,
 * or NULL if none is found.
 * We use a binary search, and thus we assume that the table is
 * already sorted.
 */
const struct exception_table_entry *
search_extable(const struct exception_table_entry *first,
	       const struct exception_table_entry *last,
	       unsigned long value)
{
	while (first <= last) {
		const struct exception_table_entry *mid;

		mid = ((last - first) >> 1) + first;
		/*
		 * careful, the distance between value and insn
		 * can be larger than MAX_LONG:
		 */
		if (mid->insn < value)
			first = mid + 1;
		else if (mid->insn > value)
			last = mid - 1;
		else
			return mid;
        }
        return NULL;
}
#endif
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